How should I adjust my hay fertilization due to high fertilizer prices?

Dr. John Fike, Extension Forage Specialist Virginia Tech

 

Fertilizer prices, particularly N, are hurting farmers in a big way. The price of nitrogen, in particular, has skyrocketed over the past year. For example, UAN28, perhaps the most popular fluid N fertilizer, started off 2021 at about $210/ton but finished the year at over $575/ton. In the same time period, potash went from about $360 to $800/ton. Similar increases occurred with phosphorus, and prices have continued to rise in the first month of January. So how does one manage around high prices? You probably can’t avoid the added fertilizer costs altogether, but if you are strategic about fertility management, you may be able to lower the impact of sky-high nutrient input costs. Here are some ideas to consider: Unless you’re a commercial hay grower, one of the best ways to lower hay fertility bills is to feed less hay.  If you’re feeding hay for much more than 60 days per year, consider working with your county agent to evaluate your situation and see how you can extend the grazing season. One of the best investments you can make in your fertility program is to test soils. Extension agents are well-known (and sometimes teased) for so often suggesting that the first step in managing field or farm is to soil test. However, as management guru Peter Drucker is often quoted, “you can’t manage what you can’t measure.” First, check your pH. Lime prices have not increased to the degree seen with synthetic fertilizers. If your soils have low pH, adding lime may provide one of the biggest bangs for the buck. Keeping pH between 6 and 7 will improve availability of phosphorus (P), potassium (K) and other nutrients. For grass and grass-clover mixes, pH above 6 will be adequate. For alfalfa or legume-based stands, pH should be 6.5 or greater. Note, however, that if you need to increase pH, it will take several months for the pH to change. Adequate pH, P and K will support legume growth that in turn will supply pastures and hayfields with  Strive to keep P and K in the medium range. Plant response to fertilizer P and K inputs diminishes as soil P and K levels increase. At today’s prices, the response to added fertility may be uneconomical if you’re applying nutrients to levels much above medium test levels. If you’re in the medium range, bide your time, hold your dollars, and wait for better prices down the road – but don’t get into a habit of not maintaining pasture and hayfield fertility! Fertilize to test. Far too often, producers have routinely applied straight blends like 10-10-10 or “triple 19” without considering a soil test. On a farm visit a few years ago, a producer was curious why their hay stand was less productive, despite continued fertilization (with a straight blend). The problem was that the added fertility inputs were not sufficient to replenish the K being removed from the hayfield. Getting a custom blend may take a bit more work, but it can be better tailored to the need, both reducing inputs and preventing overapplication of expensive and unneeded nutrients (that may also have negative environmental effects). Where possible, use alternative nutrient sources. Depending on your location (and management constraints) biosolids, poultry litter and other animal manures can offer a source of low-cost nutrients, particularly N and P, as well as organic matter. This may reduce need for N and P, but K likely will still be necessary. Feed hay back on hay ground. One may cringe at this idea given the potential to damage a hay stand. However, this can be an option and an opportunity to return nutrients to the field under the right circumstances. Feed when the ground is frozen or dry. Unrolling bales will further reduce animal impact. Many farmers may have adequate soil pH and nutrients but feel the need to add N to increase the hay crop. However, stands on fertile ground and with significant legumes may not warrant N inputs at today’s high prices. As with P and K, pounds of forage produced per unit of N input will be greater at low fertility rates. But will it pay? I dug up some numbers from a recent Kansas study looking at fescue response to N. These were newly established fields, so response to N was about 25-28 lbs. forage per lb. N. The response rate may be less in long-term, productive hayfields and pastures. If your hay field has abundant clovers or legumes, the fertility response may also be much lower.   N rate Yield lb forage   Hay value, $/ton   N cost   Value minus cost by $/ton lb/ac ton/ac per lb N   $60 $80 $100 $120   $1.03/lb   $60 $80 $100 $120         - - - - - $ per acre - - - - -       - - - - - $ per acre - - - - - 0 1.50 --     $90 $120 $150 $180   --   $90 $120 $150 $180 50 2.19 27.6   $131 $175 $219 $263     $52   $80 $124 $168 $211 100 2.83 26.5   $170 $226 $283 $339   $103   $67 $123 $180 $236 150 3.34 24.6   $210 $268 $334 $401   $155   $46 $113 $180 $247   If you do plan to fertilize cool season hay fields, try to time applications to periods of warm spring weather when forages are rapidly growing. To the extent possible, apply the fertility 1-3 days ahead of rain. Many farmers use urea as their fertilizer N source, but urea is subject to high losses (up to 40%!) from volatilization. Urea with adequate NBPT urease inhibitor will help reduce volatilization and increase use efficiency. Generally, nutrient needs for pasture soils are limited if the fields are well-managed because nutrient removal is low. However, this may not be the case where fields are overgrazed and subject to erosion. Using better grazing management can allow plants to recover and be more productive and will also improve nutrient distribution across the farm. Remember, too, that clover is the best N resource in pasture settings. Abundant and productive clovers may supply 100-150 lb. of N/acre annually.